Blog Casque : du bon son dans ses oreilles

Sept. 1, 2005: After a long hiatus, the HeadWize announcements are back. During the break, major headphone events have come and gone. Rather than looking back, this edition begins with a discussion of a long anticipated product development: Bluetooth-enabled wireless stereo headphones. Monaural Bluetooth headsets for telecommunications have been on the market for a few years, but the technology for stereo headphones is brand-spanking new and products with this technology started being released just a few months ago. Not a moment too soon. There has been pent-up demand for a non-proprietary digital wireless technology that would free portable audio consumers from the headphone cord tether.

Sept. 1, 2005: After a long hiatus, the HeadWize announcements are back. During the break, major headphone events have come and gone. Rather than looking back, this edition begins with a discussion of a long anticipated product development: Bluetooth-enabled wireless stereo headphones. Monaural Bluetooth headsets for telecommunications have been on the market for a few years, but the technology for stereo headphones is brand-spanking new and products with this technology started being released just a few months ago. Not a moment too soon. There has been pent-up demand for a non-proprietary digital wireless technology that would free portable audio consumers from the headphone cord tether.

Infrared (invisible light) and RF (radio frequency) are the two basic mediums of wireless transmission in consumer products. Both are subject to interference. RF has the wider range (it can pass through walls). The majority of RF wireless headphones today use FM encoding, an analog scheme which operates in the same crowded spectrum as FM radio and has a frequency response that tops out at 15kHz. If the audio signal were digitally encoded first before transmission, the full audio spectrum (20-20kHz) could be preserved. Digitally encoded streams are insensitive to weak signal strength and less prone to interference, because error correction circuits can compensate for distortions in the data stream. Before Bluetooth, there were (and are) wireless headphones that transmit digitally over RF. The technology in those products was proprietary and the headphones were not compatible with transmission systems of other brands.

Bluetooth offers the promise of wireless headphones that will be compatible with any Bluetooth-enabled player. Many multimedia mobile phones, personal computers and PDAs already have support for Bluetooth stereo audio streaming. When portable audio OEMs install this support in their players (there is rumor of a Bluetooth-enabled iPod), the market for these wireless headphones should take off. Industry experts predict rapid growth in this product sector over the next few years.

Of the several RF wireless technologies for data transfer in consumer electronics, Wi-Fi and Bluetooth are the best known and widely implemented. Wi-Fi is the fastest (up to 100Mbps) and has the greatest range (over 300 feet from the transmitter) and so is preferred for connecting computers to wide area networks, Bluetooth is slower with a short-range (30 feet on average) and is meant to interconnect devices in a personal area network. The current standard, Bluetooth 1.2, specifies a data rate of around 1Mbps, and under the new Bluetooth 2.0 standard, data rates can go as high as 3Mbps. Bluetooth devices draw less power, an ideal situation for battery-operated personal electronics.

Bluetooth wireless had been envisioned primarily for connecting computer peripherals (such as mice, keyboards, PDAs and digital cameras), but among the earliest, and still most pervasive, Bluetooth products were wireless telecom headsets, and especially wireless headsets for mobile phones. Jabra (formerly GN Netcom) shipped the first Bluetooth certified headset in 2000 in a somewhat bulky formfactor. By the end of 2004, the market bustled with over 100 models worldwide, each no much larger than a pack of gum. In the meantime, mobile phones evolved into multimedia devices with full-color screens and stereo output jacks. Although mobile phone owners endured listening to multimedia audio with these headsets, monaural playback was ill-suited for the immersive experience of listening to music and even gaming effects, a concern which limited their appeal to PC users.

In 2002, the Bluetooth Audio/Video Working Group (Sony, Toshiba, Nokia, Philips, Ericsson, Matsushita) addressed that shortcoming when it published the Advanced Audio Distribution Profile (A2DP), the protocol for handling high quality audio streams under Bluetooth 1.1. Because the data rate in Bluetooth 1.1/1/2 is only 1Mbps (actually 721kbps), the A2DP profile limits audio streams to 320kbps for mono and 512kbps for stereo and therefore, stereo streams must be compressed (via MP3, Bluetooth’s SBC SubBand Codec or other codec) in order to fit the Bluetooth bandwidth. By March 2003 at the CeBIT in Hannover, Germany, Toshiba unveiled a Bluetooth 1.1 stereo headphone: the SR-1 Speech Recognition Headphone. This full-size headphone with mic boom was promoted as a telecom headset for the Toshiba Dynabook’s LaLaVoice speech recognition software, but was functional as a multimeda headphone for music and DVDs.

The first lightweight Bluetooth stereo headphones appeared in 2004. As of this writing, there are probably no more than two dozen products on dealer shelves around the world, and almost all of them have an implementation of Bluetooth 1.2. This survey spans 16 models, certainly not every Bluetooth stereo headphone in existence, yet a good cross-section. The headphones were chosen to show a broad range of formfactors and features.

If at all possible, evaluate a Bluetooth headphone at the dealer before buying, and test the headphone for sound quality, comfort, compatibility, durability and reception with the intended Bluetooth source (be it an audio player, mobile phone, laptop, PDA etc.). All of the systems have a nominal transmission range of 30 feet/10 meters, but different systems may have greater range or fewer audio dropouts.

In portable electronics, the engineers often neglect sound quality in favor of specifications and features, so be prepared for disappointment if Bluetooth headphone after Bluetooth headphone does not impress you sonically. Finding the best model for your ears can take time. There are reports that some headphones cannot maintain a stable connection with the transmitter held inches away from the receiver. Put on the headphones and walk around the room and listen for dropouts. If the headphones will do double-duty as a mobile phone earpiece, have a friend call you to experience the call-switching process and voice quality (on both ends). Durability is a special concern with some neckband models, as there are reports of the neckband breaking. (Having owned neckband headphones, I can affirm that they can be as rugged and durable as other types of headphones.)

• Be mindful that not all Bluetooth-enabled audio sources are capable of transmitting a stereo audio stream. Bluetooth 1.1 and 1.2 devices must have the A2DP profile installed to recognize a stereo stream. Check the manufacturer’s website for any updates to the Bluetooth profile stack.
• Caveat Emptor: The so-called Bluetooth MP3 players out there at this writing actually require wired stereo headphones and use Bluetooth only to connect with mobile phones or to transfer audio files from personal computers. Also be on the watch for Bluetooth headphones that have an integrated MP3 player. Again, some of these use Bluetooth only to connect to mobile phones or to transfer files. They do not recognize Bluetooth stereo streams.
• Check for stereo streaming codec support. All A2DP devices must support Bluetooth’s native compression codec: SBC. Devices that support other codecs such as MP3 can be more efficient. For example, an MP3 file transmitted on a SBC-only pipe will have to be decoded first and then re-encoded with SBC. The extra processing will drain battery power.
• In addition to the volume level and play buttons, some headphones have remote track navigation buttons, which will only work with Bluetooth-enabled players that support remote control. Specifically, the player must support the Bluetooth Audio/Video Remote Control Profile (AVRCP). Some products furnish additional software to enable remote control navigation on software players like Windows Media Player.
• To use a Bluetooth headphone with a non-Bluetooth device requires the attachment of a Bluetooth transmitter (sometimes called an “audio dongle” or a “Bluetooth adapter”) to the player. Usually, the transmitters are compact and plug into any standard line/headphone output jack on a player. They operate on their own batteries, except for some iPod-specific products that draw power from the iPod itself. A transmitter will add bulk and weight to the player, and (with two exceptions) it only converts the player’s output to a Bluetooth audio stream. Navigation controls usually will not work. The two exceptions are the iPod-specific transmitters (naviPlay and iMuff) which are able to send track signals to the iPod itself.
• And speaking of bulk, the Bluetooth receiver electronics on the headphones are housed in the earpieces. The same is not true of Bluetooth stereo earbuds, which are too small to hold the electronics. Instead, the earbuds are wired to their own Bluetooth receiver. One vendor below sells a Bluetooth transmitter/receiver set, which lets users plug in their own headphones, such as earbuds or a favorite pair of wired headphones. The quality of the receiver’s internal headphone amplifier determines what headphones are a good match.

Note: Bluetooth communications are bi-directional, so use of the terms transmitter and receiver is somewhat misleading, but it does help avoid confusion.

• Broadcasting to Multiple Headphones: It is possible to connect multiple Bluetooth peripherals to a computer, but is it feasible for multiple headphones to share an audio stream broadcast from a single Bluetooth-enabled player? Based on responses from a couple of OEM tech support, broadcasting is not possible at this time. Pairing is the process whereby the Bluetooth headphones are linked to the Bluetooth player. It needs to be done each time the headphones connects to a different player. At this time, the stereo stream appears to be exclusive to one paired transmitter/receiver set.
• The headphone and adapter may be powered by an internal battery or standard disposable batteries. If they are rechargeable, compare the charge time and the operating time per charge (both the transmitter and headphones). A long playback time may be compensation for a long charge time. Some models supplement the standard AC adapter charger with a convenient USB charging cable. There are products out there with an external battery pack (no internal battery). From a convenience point of view, such solutions replace the headphone cord with a power cord.
• Owners of multimedia mobile phones will want a headphone with telcom support. One product listed below does not allow call answering and stereo streaming simultaneously. The headphone must support the Bluetooth Headset (HSP) and/or Handsfree (HFP) profiles to work with mobile phones. Other important features include an unobtrusive microphone boom or a boomless microphone, automatic switching for incoming calls or a push-to-talk button. Evaluate the connection for speech quality and volume, stability, and ease of switching. On some headphones, switching to talk requires several steps.
• Gaming headphones: Bluetooth stereo headphones with microphones can function as gaming headsets, but not all equally well. If the game does not require voice, then generally it’s not a problem. Voice complicates matters. Audio streaming is in stereo and handled by the A2DP profile. Voice communication is in mono, mediated by the HSP. Some headphones do not allow simultaneous stereo streaming and mono voice communications. If the mic is activated, the headphones may convert to mono. It’s instructive that no vendor advertises Bluetooth stereo headphones as the ideal gaming solution, despite the huge potential market.

For those who are willing to wait a season or two, more Bluetooth 2.0 headphones are coming. They will have the advantage of the faster data pipeline which could translate to higher fidelity audio (possibly with lossless compression codecs) and lower power consumption (as little as 50% of today’s models). Bluetooth 2.0 could eventually see the advent of ultra high-end wireless headphones.

Blue ant Bluetooth Stereo Headphones: The Blue ant headphones have a built-in MP3 player, but unlike other so-called Bluetooth MP3 headphones, are also authentic Bluetooth stereo headphones (running Bluetooth 1.1). The headphones can respond to a call while the MP3 player is playing, BUT call answering is NOT available when the headphones are receiving a stereo stream from a Bluetooth source. Call answering is available when listening to the internal MP3 player.

The headphones are the lightweight supra-aural type with folding neckband. A short, non-adjustable mic boom protrudes from the right earpiece for talking to a mobile phone or voice applications like iChat/Skype. There are buttons for controlling volume, connect (a mobile phone talk button) and play. The right earpiece holds the LiPolymer battery pack, which can be ejected for recharge in enclosed AC charger (may need an adapter outside Australia). Charge time is about 2 hours for an operating time between 3.5 and 7 hours depending on use (175 hours on standby).

The internal audio player contains 128Mb flash memory (non-expandable) and plays MP3/WMA encoded files. This device also supports audio streaming in MP3/WMA/SBC formats. The packaging includes a USB Bluetooth transmitter for personal computers and software for Windows computers that lets users control playback from the PC. The Play/Connect buttons can serve as next/previous track navigation. The headphones weigh 76gr with battery. MSRP is $299 (AUD).

BlueTake BT420EX: BlueTake Technology brought out these headphones in the middle of 2004 and may be the first vendor to market with a lightweight Bluetooth stereo headphone - and running Bluetooth 2.0 no less. BT420EX is billed as a “sports headphone” due to the secure fit of the foldable neckband during strenuous activity. The right earpiece has volume control and talk buttons, a status LED and a mic boom that swings down. The left earpiece holds the Lithium Polymer battery, a LED power indicator, a recharge port and a power switch. Operating time is 6 hours (music) and 8 hours (talk) for a 5-hour charge time. Included in the package are a Bluetooth transmitter (powered by a rechargeable LiPolymer battery), velcro straps (for attaching the transmitter to non-Bluetooth players), an AC adapter (check configuration for local line voltage) and USB charging cable, several color plates to customize the headphones. Audio streaming is via SBC compression. The headphones weigh 98 gr. MSRP $250 US.

Creative Labs CB2530: The CB2530 is available in black or white. Creative has styled these headphones to match their Zen players. The earcups are fitted with interchangeable color rings in black and white. The right earcup has a volume jog dial and on/off switch. Operates on 2 standard AAA batteries in the left earcup for up to 8 hours. The included Bluetooth transmitter plugs into a player’s headphone jack and runs on a single AA battery. The headphones weigh 203 gr. with batteries. MSRP is $140 US.

iTech Nightingale BSH 338: In this Bluetooth earbud solution, the receiver electronics are housed inside a clip-type formfactor (several color choices). One of the earbuds can be detached for conversion to monaural - but the other one is permanent. iTech is selling the BSH338 as a PC/PDA solution. No Bluetooth transmitter is included. The only controls on the clip are volume up/down. The on/off/call answer button is embedded in the grip of the permanent earbud. For voice/mobile phone connectivity, there is a microphone and a buzzer built into the clip. The buzzer activates on incoming calls. The LiPolymer battery in the clip operates up to 6 hours on music/talk or 150 hours on standby. Charge time is 3 hours via an AC adapter that plugs into the side of the clip. The earbuds plus clip weigh 27 gr. MSRP: 40 UKP.

Logitech Wireless Headphones for PC, Hewlett Packard FA303, Toshiba PA1831 : These headphones are grouped together because they appear to be sourced from a single OEM: Logitech. This neckband-style model is targeted to PC/PDA users only. None of them includes a transmitter for non-Bluetooth audio players (one does have a USB Bluetooth transmitter) and there is no telecom support. All of the control functionality is located on the right earpiece: volume, track navigation, recharge port and a large (multifunction button) MFB in the center for play/pause/power on/off. Battery life is 8 hours for a 4-hour charge time.

These come with similar accessories, but there are differences. Logitech supplies a USB Bluetooth transmitter for a laptop or PC and software for Windows computers. The HP FA303 is branded for iPAQ owners. There are software drivers for various iPAQ models and an AC adapter that can charge the headphones and an IPAQ. The Toshiba packaging does not have a Bluetooth transmitter or software, but the latest Bluetooth stack for Windows XP can be downloaded from Toshiba Support.MSRP: Logitech Wireless - $130 US, HP FA303 - $100 US, Toshiba PA1831 - $99.

Macally BlueWave: Stylistically designed for the Apple iPod, the BlueWave is the only full-size, closed headphone in this survey. The earcups fold into the headband. The rectangular-shaped Bluetooth transmitter has the same width/depth profile as an iPod and plugs into any standard headphone/line output. There is an output port on one earcup that can connect to a home audio system. The other controls for volume, power on/off and a LED indicator. The Bluetooth transmitter is a stylistic match for the iPod and plugs into the iPod’s headphone jack. The headphones and transmitter each take 2 AA batteries and operate up to 48 hours. The headphones weigh 170 gr. without batteries. MSRP is $170 US.

Motorola HT820: Each earpiece on this this neckband-style headphone has a large multifunction button printed with the Motorola logo in the center. The MFB on the right earpiece controls music playback and smaller buttons implement track navigation. The right earpiece also contains an integrated microphone. The MFB on the left earpiece controls call answering and there are smaller buttons for volume. The Bluetooth circuity can be bypassed by plugging an audio source into a submini-jack (2.5mm) on the side of the right earpiece. Battery life is 14 hours music, 17 hours talk and 500 hours standby. There is a mini-USB port for charging the battery, but only an AC adapter is supplied (no USB charging cable). Check for international line voltage support. MSRP not available. Street pricing varies from $80 to $170 US.

Omiz OMS600: The OMS600 is packed with features: stereo Bluetooth headphone, MP3/WMA player with SD memory expansion slot, FM tuner, LCD display and voice support via an internal microphone. A Bluetooth adapter for non-Bluetooth players is an optional accessory. The right earpiece holds the LCD, SD slot, a mini-USB jack, track navigation and volume buttons and a mode button for switching between functions. The left earpiece holds the LiPolymer battery and power button. 128Mb of internal flash memory (expandable to 1G via the SD slot) can store MP3 or other music files and may also store non-music files. Recharge time (via the enclosed USB port cable or the travel AC adapter) is 2 hours for up to 8 hours of operating time. Weight: 88 gr. with battery. MSRP: 120 UKP.

Plantronics Pulsar 590: The 590 is a lightweight, supra-aural headphone with folding earcups. The right earcup has a short telescoping mic boom and buttons for: volume, track navigation, call handling. Audio streaming via SBC compression. The disc-shaped Bluetooth transmitter plugs into any source with a standard headphone/line out jack. Both the headphones and Bluetooth transmitter run off internal Lithium Polymer batteries (on the headphones, stored in the left earcup) which last 10 hours (music) to 12 hours (talk or 130 hours standby) per charge. Recharging takes 2 hours via the desktop charging stand or USB charging cable. An “in-flight” cable converts the 590 into a standard wired headphone by disabling the Bluetooth circuitry for use on airplanes. Headphone weight: 97 gr. MSRP: $150 US for headphones alone, $200 for headphones and Bluetooth transmitter.

Sonorix OBH-0110: This folding neckband headphone has a detachable microphone boom for voice applications. On the left earpiece are two triangular MFB buttons (one for play/pause/call answer, one for power on/off/stop), two smaller buttons for volume control and a microphone port. The right earpiece holds the detachable LiPolymer battery that can be recharged via a mini-USB port. The battery runs for 12 hours (over 200 hours in standby mode) on a 2-hour charge. Among the included accessories are a matching Bluetooth transmitter for non-Bluetooth devices, two USB recharging cables, an AC adapter. Weight: 76 gr. with battery. MSRP: $175 US.

Ten Technology naviPlay: Designed specifically for the Apple iPod, this is a Bluetooth transmitter and receiver (called a “remote”) set but no headphones. Instead, users plug their own headphones into the remote pack, which also sports an internal microphone for voice application/mobile phone connectivity. The remote has buttons for Power/Play and a multi-function “Navi” button for controlling volume, track navigation, and call answer.

naviPlay’s transmitter pack clips onto the iPod and is incompatible with other audio players. One advantage to the iPod customization is that the track navigation controls on the remote work. Although the transmitter and receiver are paired, they can be unpaired so that each can communicate with other Bluetooth-enabled devices. Ten Technology markets the naviPlay as a wireless product for headphones, powered speakers and other applications requiring wireless connectivity (such as connecting an iPod to a home stereo system).

Other specs: The audio codec is SBC. LiPolymer batteries power the remote and transmitter up to 8 hours (4-hour charge time). The packaging has an AC adapter and FireWire charging cable. The remote weighs 46 gr. MSRP $239 US.

WiGear iMuff: One of three products in this survey that supports the Bluetooth 2.0 standard. Styled to match the Apple iPod, the neckband formfactor features an internal microphone for for talking to a mobile phone or PC (iChat or Skype). When the cellphone rings, the iMuff automatically pauses playback and answers the incoming call. On the right earpiece are buttons for Play, Left and Right (track navigation). The left earpiece has the Lithium Polymer battery that can be recharged from a USB port or the included AC adapter and runs up to 16 hours. The really tiny Bluetooth transmitter appears to take power directly from the iPod. The compression codec is SBC, and achieves “near CD” quality - although it is not clear if the compression rate is any different from a Bluetooth 1.2 device. MSRP is $180 US.

Xterasys BPMH203: This is the second Bluetooth stereo headphone from Xterasys; the first one was the BSH201. This model adds a collapsible neckband, Bluetooth transmitter for non-Bluetooth devices (the 201 had a USB adapter, which limited its use to PCs), a microphone for voice applications, a rechargeable LiPolymer battery, automatic pairing between the headphones and the transmitter and Bluetooth 2.0. Volume and navigation controls are on the left earpiece. On the right earpiece is a single MFB for play/mute/call answer/call reject/power on/off and a recharge port. Audio streams are compressed with the SBC codec. Battery life is over 5 hours on a single charge. Weight: 62 gr. MSRP: $111 US.